I'm trying to get the time delta in minutes between two times. The query returned incorrect time deltas:
time_delta should be 133 and 90 respectively.
SELECT arrival_time, discharge_time
,STRFTIME("%H%M", discharge_time)-STRFTIME("%H%M", arrival_time) AS time_delta
FROM table;
Your query does not work because it converts the dates to string representations (in format %H%M), then it tries to substract the two strings - which does not do what you expect.
You can, instead, convert the dates to unix epochs, so you get a time difference in seconds :
select arrival_time, discharge_time,
unixepoch(discharge_time) - unixepoch(arrival_time) as time_delta_in_seconds
from mytable;
unixepoch() is a syntax shortcut for strftime('%s', ...), as explained in the SQLite documentation.
Been trying to change a native SAS datetime value to an oracle one-
ie. 1788130680 converts to 29AUG2016:22:58:00
I had attempted to do this:
to_date('01/01/1960','DD/MM/YYYY')+ 1788130680
but no dice. Suggestions appreciated.
Thank you.
It looks like you have a number of seconds since January 1st, 1960. You can turn it to a date as follows:
date '1960-01-01' + 1788130680 / 60 / 60 / 24
The idea is to conver the number to days (by dividing it by the number of seconds there is in a day), and then add it to the starting date.
It might be easier to understand by using an interval:
date '1960-01-01' + 1788130680 * interval '1' second
Im new using sql, i tried to convert interval to minutes. Is there a developed function that did this.
Thank you
You can use epoch and divide by 60.
select extract(epoch from <date>) / 60
extract(epoch) gives the number of seconds since 1970-01-01. So, this gives the number of minutes since 1970-01-01, which seems like a reasonable interpretation of your question.
I suppose from tag that you use PostgreSql.
Postgresql has a very good documentation. In this link you can find all the date-time functions.
In your case you can use this function to truncate date to minute part:
date_trunc(text, timestamp)
date_trunc('minute', date_column)
If you need the timestamp, you can cast to timestamp ::timestamp and then convert to minutes
I need some help with timestamps with postgresql. I have a column for the timestamp with timezone named download_at for when a user downloaded an app and a column user_id which is an integer. I am trying to extract user IDs of users that have downloaded within the last 168 hours from the last 60 days of information. I am a bit confused on how I can approach this and felt stuck because of the two different times. I believe I might have to play around with the trunc function but felt a bit stuck.
A basic example:
SELECT *
FROM table1
WHERE download_at > now() - '186 hours'::interval
Postgres is phenomenal at handling dates and times. A breakdown of what this does:
now() --function that returns the current time as a datetime object
'186 hours'::interval --a string cast to an interval
In postgres :: does casting. When casting to an interval Postgres will turn formatted English to an interval object. Since you can subtract datetime and interval objects it'll do the rest for you.
Is there a TIMESTAMPDIFF() equivalent for PostgreSQL?
I know I can subtract two timestamps to get a postgresql INTERVAL. I just want the difference between the two timestamps in in hours represented by an INT.
I can do this in MySQL like this:
TIMESTAMPDIFF(HOUR, links.created, NOW())
I just need the difference between two timestamps in hours represented as an integer.
Solution works for me:
SELECT "links_link"."created",
"links_link"."title",
(EXTRACT(EPOCH FROM current_timestamp - "links_link"."created")/3600)::Integer AS "age"
FROM "links_link"
The first things popping up
EXTRACT(EPOCH FROM current_timestamp-somedate)/3600
May not be pretty, but unblocks the road. Could be prettier if division of interval by interval was defined.
Edit: if you want it greater than zero either use abs or greatest(...,0). Whichever suits your intention.
Edit++: the reason why I didn't use age is that age with a single argument, to quote the documentation: Subtract from current_date (at midnight). Meaning you don't get an accurate "age" unless running at midnight. Right now it's almost 1am here:
select age(current_timestamp);
age
------------------
-00:52:40.826309
(1 row)
Get fields where a timestamp is greater than date in postgresql:
SELECT * from yourtable
WHERE your_timestamp_field > to_date('05 Dec 2000', 'DD Mon YYYY');
Subtract minutes from timestamp in postgresql:
SELECT * from yourtable
WHERE your_timestamp_field > current_timestamp - interval '5 minutes'
Subtract hours from timestamp in postgresql:
SELECT * from yourtable
WHERE your_timestamp_field > current_timestamp - interval '5 hours'
Michael Krelin's answer is close is not entirely safe, since it can be wrong in rare situations. The problem is that intervals in PostgreSQL do not have context with regards to things like daylight savings. Intervals store things internally as months, days, and seconds. Months aren't an issue in this case since subtracting two timestamps just use days and seconds but 'days' can be a problem.
If your subtraction involves daylight savings change-overs, a particular day might be considered 23 or 25 hours respectively. The interval will take that into account, which is useful for knowing the amount of days that passed in the symbolic sense but it would give an incorrect number of the actual hours that passed. Epoch on the interval will just multiply all days by 24 hours.
For example, if a full 'short' day passes and an additional hour of the next day, the interval will be recorded as one day and one hour. Which converted to epoch/3600 is 25 hours. But in reality 23 hours + 1 hour should be a total of 24 hours.
So the safer method is:
(EXTRACT(EPOCH FROM current_timestamp) - EXTRACT(EPOCH FROM somedate))/3600
As Michael mentioned in his follow-up comment, you'll also probably want to use floor() or round() to get the result as an integer value.
You can use the "extract" or "date_part" functions on intervals as well as timestamps, but I don't think that does what you want. For example, it gives 3 for an interval of '2 days, 3 hours'. However, you can convert an interval to a number of seconds by specifying 'epoch' as the time element you want: extract(epoch from '2 days, 3 hours'::interval) returns 183600 (which you then divide by 3600 to convert seconds to hours).
So, putting this all together, you get basically Michael's answer: extract(epoch from timestamp1 - timestamp2)/3600. Since you don't seem to care about which timestamp precedes which, you probably want to wrap that in abs:
SELECT abs(extract(epoch from timestamp1 - timestamp2)/3600)
postgresql get seconds difference between timestamps
SELECT (
(extract (epoch from (
'2012-01-01 18:25:00'::timestamp - '2012-01-01 18:25:02'::timestamp
)
)
)
)::integer
which prints:
-2
Because the timestamps are two seconds apart. Take the number and divide by 60 to get minutes, divide by 60 again to get hours.
extract(hour from age(now(),links.created)) gives you a floor-rounded count of the hour difference.
To avoid the epoch conversion you could extract the days multiply them by 24 and add the extraction of hours to it.
select current_timestamp, (current_timestamp - interval '500' hour), (extract(day from (current_timestamp - (current_timestamp - interval '500' hour)) * 24) + extract(hour from (current_timestamp - (current_timestamp - interval '500' hour))));
For MySQL timestampdiff I don't know, but for MSSQL datediff(hour, start, end) the best equivalent in PostgreSQL is floor(extract(epoch from end - start)/3600), because in MSSQL select datediff(hour,'2021-10-31 18:00:00.000', '2021-10-31 18:59:59.999') return 0
This might sound crazy to a lot of developers who like to take advantage of database functions,
But after exhaustive problems thinking, creating and bugfixing applications for mysql and postgrsql with php comparing date functions, I've come to the conclusion (for myself), that the easiest way, that is the simplest with less SQL headaches is not to take advantage of any of them.
Why? because if you are developing in a middleware language like PHP, PHP has all of these functions, and they are easier to implement in the application ode as comparing integers. PostgreSQL timestamp is NOT == UNIX TIMESTAMP and MySQL's UNIX TIMESTAMP is NOT PostgresQL's or Oracles timestamp.. it gets harder to port if you use database timestamps..
so just use an integer, not a timestamp,
as the number of seconds since january 1st 1970 midnight. and never mind database timestamps.
, and use gmdate() and store everything as gmt time to avoid timezone issues.
if you need to search, sort or compare the day from other data, or the month or the year or the day of the week, or anything, in your application,
and INTEGER datatype for time_day, time_hour, time_seconds.. or whatever you wnat to index to be searched will make for smoother and more portable databases.
you can just use one field, in most instances: INTEGER time_created NOT NULL
(more fields in your database row is the only drawback to this solution that i have found, and that doesnt cause as many headaches, or cups of coffee :)
php's date functions are outstanding to compare dates,
but in mysql or postgresql, comparing dates ? nah.. use integer sql comparisons
i realize it may SEEM easier to use CURRENT_TIMESTAMP on an insert function. HA!
don't be fooled.
You cant do DELETE FROM SESSION_TABLE WHERE time-initialized < '2 days'
if time-intitialized is a postgresql timestamp.
but you CAN do:
DELETE FROM SESSION_TABLE WHERE time_initialized < '$yesterday'
As long as you set $yesterday in php as the integer of seconds since 1970 that yesterday was.
This is easier housekeeping of session records than comparing timestamps in postgresql select statements.
SELECT age(), SELECT extract(), and asbtime are headaches in an of themselves. this is just my opinion.
you can do addition, substraction, <, >, all with php date objects
_peter_sysko
U4EA Networks, Inc.